Electric motors that have found wide application in various sectors of industry Have unique features such as high reliability, high efficiency, quick acceleration and have small sizes. Brushless DC motors meet these requirements well. In this study, the design of a brushless DC motor speed limits for the particular application at 1800 rpm that can be equivalent to 140 watts output was provided.Aims to increase the power density, efficiency and reduce engine weight by using the finite element method. according to the analysis of the existing motors and parameter extraction, comparing them with software for high electromagnetic torque and low weight , in this article we have focused on the permanent magnet by testing with different types of magnets and comparing the results of finite element analysis. The existing magnets made of ceramics with the lowest density , but the permanent magnet in software method has the highest energy density.